Optical glasses

Abstract

An optical glass having a high dispersion and a refractive index in the range of from 1.53 to 1.86 and an Abbe number in the range of from 21 to 43 comprises substantially the following components in percent by weight: P2O5: 10-72 RI2O: 0-41 ZnO: 0-46 (provided that RI2O + ZnO: 5-50) Nb2O5: 22-63 wherein RI2O is Li2O, Na2O or K2O or combination of two or more thereof.

We claim: 
     
       1. An optical glass composition having a high dispersion and a refractive index in the range of from 1.53 to 1.86 and Abbe number in the range of from 21 to 43, said glass composition consisting essentially of, in percent by weight, the components of: P 2  O 5  : 10-52   R I   2  O: 0-34   ZnO: 0-35 (wherein, R I   2  O+ZnO: 5-40)     Nb 2  O 5  : 24-63   TiO 5  : 1-26   Al 2  O 3  : 0-14   R II  O: 0-40   PbO: 0-32   GeO 2  : 0-55   Ta 2  O 5  : 0-22   WO 3  : 0-47   F: 0-16   SiO 2  : 0-4   Y 2  O 3  : 0-6   ZrO 2  : 0-5   La 2  O 3  : 0-4 wherein, R I   2  O is Li 2  O, Na 2  O or K 2  O or combination of two or more thereof, and   wherein R II  O is MgO, CaO, SrO, or BaO or combination of two or more thereof.     
     
     
       2. An optical glass composition having a high dispersion as claimed in claim 1, wherein said glass composition comprises, in percent by weight: P 2  O 5  : 10-42   R I   2  O: 0-32   R II  O: 0-32.   
     
     
       3. An optical glass composition having a high dispersion as claimed in claim 2, wherein said glass composition comprises, in percent by weight: P 2  O 5  : 18-42   R I   2  O: 0-32   ZnO: 0-35 (wherein, R I   2  O+ZnO: 12-40)     Nb 2  O 5  : 24-45   TiO 2  : 1-22   GeO 2  : 0-40   WO 3  : 0-35.   
     
     
       4. An optical glass composition having a high dispersion as claimed in claim 3, wherein said glass composition comprises, in percent by weight, the components of: P 2  O 5  : 24-38   R I   2  O: 10-26   ZnO: 0-15 (wherein, R I   2  O+ZnO: 12-27)     Nb 2  O 5  : 24-40   TiO 2  : 1-19   Al 2  O 3  : 1-12   R II  O: 0-15   PbO: 0-20   GeO 2  : 0-20   Ta 2  O 5  : 0-10   WO 3  : 0-20   F: 0-6   SiO 2  : 0-3.